Some of the “material authors” of the apparent attack have been detained he said, adding: “The investigation will get to the bottom of this.”

Venezuela’s government routinely accuses opposition activists of plotting to attack and overthrow Mr Maduro, a deeply unpopular leader who was recently elected to a new term in office in a vote decried by dozens of nations.

He has steadily moved to concentrate power as the nation reels from a crippling economic crisis.

A couple walks away from the venue where the government said that a drone armed with explosives detonated near Venezuelan President Nicolas Maduro (Fernando Llano/AP)

In the midst of near-daily protests last year, a rogue police officer flew a stolen helicopter over the capital and launched grenades at several government buildings. Oscar Perez was later killed in a deadly gun battle after over six months on the run.

Attorney General Tarek William Saab said the attempted assassination targeted not only Mr Maduro, but rather the military’s entire high command on stage with the president.

Prosecutors have already launched their investigation and obtained critical details from the suspects in custody, said Mr Saab, adding that he would give more details on Monday.

“We are in the midst of a wave of civil war in Venezuela,” he said.

Firefighters at the scene of the blast disputed the government’s version of events.

Three local authorities said there had been a gas tank explosion inside an apartment near Mr Maduro’s speech where smoke could be seen streaming out of a window. They provided no further details on how they had reached that conclusion.

A Colombian official with the president’s office described Mr Maduro’s claims that Santos was involved in the attack as baseless.

Adding to the confusion, a little known group calling itself Soldiers in T-shirts claimed responsibility, saying it planned to fly two drones loaded with explosives at the president, but government soldiers shot them down before reaching its target.

Whoever did this, he'll use it to further restrict liberty and purge the government and armed forces

“We showed that they are vulnerable,” the group said in a tweet. “It was not successful today, but it is just a matter of time.”

David Smilde, a senior fellow at the Washington Office on Latin America who has spent decades researching Venezuela, said the incident did not appear to be a staged attack by Mr Maduro’s government for political gain.

The “amateurish” attack prompted embarrassing images of Maduro cut off mid-sentence with droves of soldiers running away in fear, making the president appear vulnerable, Mr Smilde said.

“He will use it to concentrate power,” he said. “Whoever did this, he’ll use it to further restrict liberty and purge the government and armed forces.”